1. Field of the Invention
The present invention relates to a mobile radio apparatus for a portable telephone and the like which is desired to be operated with low power consumption.
2. Description of the Related Art
FIG. 7 is a schematic diagram illustrating a conventional mobile radio apparatus. As an example of the mobile radio apparatus, a portable telephone is shown. In FIG. 7, reference numerals 21 and 22 denote antennas. The antenna 21 is a receiving antenna, while the antenna 22 is operated as a transmitting antenna upon transmission and is operated as a receiving antenna upon reception to perform diversity reception together with the antenna 21. Numeral 23 denotes a receiving circuit for amplifying a received signal. Numeral 24 denotes a demodulation circuit which demodulates a baseband signal from the received signal to obtain digital data and reproduces a clock from the received signal. Numeral 25 denotes a voice decoding circuit which converts the digital data into an analog voice signal. Numeral 26 denotes a voice encoding circuit for converting an analog voice signal into a digital data. Numeral 27 denotes a modulation circuit for performing modulation in accordance with modulation systems by using the digital data. Numeral 28 denotes a transmitting circuit for amplifying a modulated signal. Numeral 30 denotes a timing control circuit for controlling the timing for the whole mobile radio apparatus.
Among operations of the mobile radio apparatus shown in FIG. 7, operation of an intermittent receiving mode upon waiting for reception and position registration, specifically, is now described. Upon waiting for reception, objects to be supplied with the clock from the timing control circuit 30 are minimized and a power supply for supplying power to the receiving circuit 23 and the demodulation circuit 24 is turned on only during slots for necessary information, while the voice decoding circuit 25, the voice encoding circuit 26, the modulation circuit 27 and the transmitting circuit 28 are put into a standby mode. In this manner, the mobile radio apparatus is switched to an intermittent receiving mode. In the intermittent receiving mode, several intermittent receiving operations are made for several hundred milliseconds and only necessary information is received, to reduce the power consumption while waiting for reception and to lengthen the waiting for reception capability for one charging of a battery. When a simultaneous calling area in which a user of the mobile radio apparatus is located is changed because of variation of a reception level due to movement of the user, the position registration is required for recognizing the position of the mobile radio apparatus to a base station of a portable telephone network for a changed simultaneous calling area and transmission is made for the position registration. The transmission is made only upon the position registration operation, while it is necessary to reduce the power consumption at this time as small as possible.
However, in the conventional mobile radio apparatus constituted by the portable telephone by way of example, the intermittent receiving operation is performed to lengthen the time capable of waiting for reception for one charging of the battery, while the waitable time is only about several tens of hours and the charging of the battery is required frequently.
Further, in order to reduce a power consumption, a mobile radio apparatus including a pager combined with the portable telephone is disclosed in JP-A-61-67336 and JP-A-5-102924. In such a mobile radio apparatus, only the pager unit is operated while waiting for reception and the portable telephone is supplied with power after a calling signal has been received, so that a reduction of power consumption during the waiting for reception is effected.
In the abovementioned papers, however, the position registration in the case where the user of the mobile radio apparatus is moved is not described. Generally, in the mobile radio apparatus such as the portable telephone, each time the simultaneous calling area in which the user of the portable telephone is located is changed to a new area, the position registration is required to recognize the position of the user of the portable telephone to the base station of the portable telephone network for the new area. Although one transmission time for the position registration is short, the power consumption for each transmission is large and this is a great problem encountered when the power consumption of the whole apparatus is made smaller.